Local area network assisted positioning

ABSTRACT

A method for assisting in locating a position of a mobile wireless device includes: obtaining location information of an approximate location of the mobile wireless device; generating an almanac of base stations based at least in part on proximity of locations of the base stations to the approximate location of the mobile wireless device, the almanac of base stations comprising at least one cooperative terrestrial base station that can communicate with the mobile wireless device in at least one mode and at least one uncooperative terrestrial base station capable of bi-directional communications and configured to prevent data and voice communications with the mobile wireless device, the at least one uncooperative terrestrial base station being configured to acknowledge a message received from the mobile wireless device; and providing the almanac of base stations to the mobile wireless device.

This application claims the benefit of and is a continuation of U.S.application Ser. No. 15/404,834, entitled “Local Area Network AssistedPositioning,” filed on Jan. 12, 2017, which claims the benefit of and isa continuation of U.S. application Ser. No. 13/655,300, entitled “LocalArea Network Assisted Positioning,” filed on Oct. 18, 2012, which claimsthe benefit of and is a continuation of U.S. application Ser. No.10/936,130, entitled “Local Area Network Assisted Positioning,” filed onSep. 7, 2004, which claims the benefit of and is a continuation in partof U.S. application Ser. No. 10/877,205, entitled “Method and Apparatusfor Wireless Network Hybrid Positioning,” filed on Jun. 25, 2004, whichclaims the benefit of U.S. Provisional Application Ser. No. 60/483,094,entitled “Method and Apparatus for Wireless Network Hybrid Positioning,”filed on Jun. 27, 2003; and U.S. application Ser. No. 10/936,130 alsoclaims the benefit of and is a continuation in part of US PCTApplication Serial No. PCT/US04/20920, entitled “Method and Apparatusfor Wireless Network Hybrid Positioning,” filed on 28 Jun. 2004, whichclaims priority to U.S. Provisional Application Ser. No. 60/483,094,entitled “Method and Apparatus for Wireless Network Hybrid Positioning,”filed on Jun. 27, 2003.

BACKGROUND

This disclosure relates in general to automated location determinationand, more specifically, but not by way of limitation, to determining alocation of a wireless device.

There is an ever growing desire to know geographic position of variousmobile devices. For example, cellular phone operators are trying tocomply with requirements to locate handsets for emergency purposes. Onceposition is known, emergency personnel can be dispatched to aidresolving the emergency. Knowing geographic location serves many otherpurposes such as geographic-tied advertising, child supervision,automated parolee supervision, reverse 911, fleet vehicle tracking, etc.

Conventional location techniques have difficulty accurately resolvinglocation in certain situations. Satellite-based location systems sufferfrom inaccuracies when a clear view the sky is unavailable.Terrestrial-based systems require communication with several basestations that serve as known references during trilateration, but insome scenarios, since these systems were primarily designed forcommunication purposes there are not enough geographically dispersedbase stations within communication range of the mobile device. Even whencommunication is possible to multiple base stations, multi-path inducedinaccuracies can degrade the ability to resolve an accurate location.

Conventional location techniques have a wireless phone interacting withbase stations associated with the service to which the wireless phone issubscribed. An almanac of base stations indicates to the wireless phonewhere the base stations are located. On most occasions, at least coupleof base stations are visible to the wireless phone.

Cellular phones often have limited memory to store additionalinformation. Base stations are constantly being added, removed orrelocated in a cellular phone network. Almanacs of base stations areoccasionally sent to cellular phones to aid in determining location. Tocommunicate and store a large almanac is impractical on some cellularphones.

SUMMARY

A method and system that allow resolving the location of a wirelessdevice are disclosed. Resolving the location in one embodiment reliesupon accessing at least one cooperative base station and at least oneuncooperative base station. The cooperative base station provides analmanac of base stations that are likely to be near the wireless device.Both cooperative and uncooperative base stations within range can beused to determine the location of the wireless device. The uncooperativebase station is not generally available to the wireless device, but canbe used to determine distance to the wireless device. An attempt by thewireless device to transport data or voice on the uncooperative basestation may or may not be thwarted by the uncooperative base station.

In one embodiment, the population of base stations is reduced to producea tailored almanac of base stations. The tailored almanac includesinformation to uniquely identify each base station, and may includelocation information for the base stations.

In another embodiment, any number of different base station types can beused. The base station could be a cellular phone base station, awireless local area network, a wireless wide area network, a satellite,a terrestrial location beacon, or any other device that can wirelesslycommunicate in some mode with the wireless device in a manner thatallows unique identification of the device and a distance measurement.

In a variety of other embodiments the general location of the wirelessdevice is determined in different ways. Various embodiments might usethe location function integral to the phone, the current cooperativebase station and a presumed cell footprint, a number of base stations tofind an overlapping cell footprint, a number of cooperative basestations to trilaterate the position, base stations and satellites totrilaterate the position, and/or one or more cooperative base stationsthat can determine range and angle. Different wireless devices havedifferent capabilities, as do base stations, such that there could be anumber of approaches used.

BRIEF DESCRIPTION OF THE DRAWING

The features, objects, and advantages of embodiments of the disclosurewill become more apparent from the detailed description set forth belowwhen taken in conjunction with the drawings, in which like elements bearlike reference numerals. Further, various components of the same typemay be distinguished by following the reference label by a dash and asecond label that distinguishes among the similar components. If onlythe first reference label is used in the specification, the descriptionis applicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

FIGS. 1A, 1B and 1C are a block diagrams of embodiments of a locationdetermination system;

FIGS. 2A and 2B are diagrams of embodiments of a single-cell locationsystem;

FIGS. 3A and 3B are diagrams of embodiments of a cell sector locationsystem;

FIG. 4 is a diagram of an embodiment of an overlapping cell locationsystem;

FIG. 5 is a diagram of an embodiment of a trilateration cell system;

FIG. 6 is a diagram of an embodiment of a hybrid trilateration system;

FIG. 7 is a diagram of an embodiment of an angular ranging system;

FIG. 8 is a flow diagram of an embodiment of a process for locating aposition of a wireless device that has native location functions;

FIG. 9 is a flow diagram of another embodiment of a process for locatinga position of a wireless device that has limited location functions;

FIG. 10 is a diagram of an embodiment of system that gathers locationinformation from uncooperative base stations;

FIG. 11 is a flow diagram of an embodiment of a process for gatheringlocation information from base stations; and

FIG. 12 is a diagram of another embodiment of system that gatherslocation information from uncooperative base stations.

DETAILED DESCRIPTION

Referring initially to FIG. 1A, a block diagram of an embodiment of alocation determination system 100-1 is shown. The location determinationsystem 100 allows wireless devices 120 to find their geographic locationor be located by remote entities by using satellites 152 (e.g., GLONASS,GPS, Galileo, EGNOS, Globalstar, IRIDIUM) and/or base stations 112,124(e.g., cellular phone base station, a wireless local area network, awireless wide area network, satellite phone, satellite Internet, or anyother device that can be uniquely recognized and communicate with thewireless device 120). Cooperative base stations 112 are coupled to analmanac processor 122 by way of a wide area network (WAN) 110 in thisembodiment, but other embodiments could use a local area network (LAN).The almanac processor 122 accesses a base station database 144 to tailoror customize an almanac according to the estimated location of thewireless device 120.

A wireless device 120 can communicate with any number of devices toprovide location information. In this embodiment, the wireless device120 is a cellular phone that may have any number or combination ofcommunication modes (e.g., GSM, CDMA, TDMA, WCDMA, OFDM, GPRS, EV-DO,WiFi, Bluetooth, WiMAX, 802.xx, UWB, satellite, etc.) to transfer voiceand/or data with cellular, satellite, wireless data, and/or meshnetworks by way of their base stations 112,124. The wireless device 120in other embodiments could be a tracking device, a child or paroleemonitor, navigational device, wireless pager, wireless computer, PDA,asset tag, etc.

The supported communication modes for each wireless device 120 arestored in a device capability database 140 that includes information tohelp in determining an uncertainty factor for each location or distancemeasurement made by a particular wireless device 120 operating in anynumber of communication modes.

This embodiment shows cooperative base stations 112, uncooperative basestations 124 and a satellite location beacon 152 that could each havedifferent communication modes. For example, cellular base stations112,124 might support TDMA and GSM, a satellite base station mightsupport only CDMA, or another satellite base station might support onlyTDMA.

Base stations 112,124 are defined herein to allow some sort of dataand/or voice transport. Base stations 112,124 are often affiliated withsome entity (e.g., cellular or WiFi service provider) such that onlysubscribers or subscribers to another system with a roaming agreementcan communicate with the base station 112,124 to pass data and/or voicetraffic. The base stations 112,124 may be connected to a WAN or LAN toget a tailored almanac, but only cooperative base stations 112 provide atailored almanac. The various base stations 112,124 may have any numberof or combination of communication modes (e.g., GSM, CDMA, TDMA, WCDMA,OFDM, GPRS, EV-DO, WiFi, Bluetooth, WiMAX, 802.xx, UWB, satellite, etc.)to transfer voice and/or data with cellular, satellite, wireless data,and/or mesh networks.

There are cooperative and uncooperative base stations 112,124. Ancooperative base station 112 is one that allows data and/or voicecommunication with the wireless device 120. In one example, voicecommunication can be supported by Voice over IP (VoIP). Uncooperativebase stations 124 may not allow data and/or voice traffic, but doprovide information useful in determining a location of the wirelessdevice. Uncooperative base stations 124 provide some type of identifierand can often be used for ranging, which is a process where the distancebetween the base station 124 and the wireless device 120 is determined.The identifier in the case of a WiFi base station 124, for example,includes a station identifier and MAC address. Also, some uncooperativebase stations 124 allow ranging measurements, received signal strengthindications and beacon signaling capabilities that can all be used todetermine distance.

The base station database 144 stores the identifier information that canbe used to uniquely identify each base station in that class of basestations. For example, each WiFi base station could include a MACaddress as identifier information. As another example, a CDMA basestation identifier could include SID, NID and Base ID or SID, MSC ID andBase ID. Characteristics of the base station 112,124 could be used inuniquely identifying the base station 112,124. For example, if two basestations had the same station identifier, but only one supported aparticular communication standard, the two could be uniquely identified.Typically, a wireless device 120 would support a subset of the variouscommunication modes. Also stored in the base station database 144 islocation information that is determined for each base station 112,124 byperforming surveys of the area with the wireless devices.

In one embodiment, wireless devices 120 can be used to determine thelocation of each base station 112,124, thereafter the location isreported back to the almanac processor 112. The location informationfrom various wireless devices 120 for each base station 112,124 isaggregated by the almanac processor 112 to update the base stationdatabase. As more location data points are gathered, they are weightedaccording to the accuracy of the location information provided by thewireless device 120 and used to resolve the location of the base stationwith ever increasing accuracy. The accuracy of each wireless device 120could be stored in the device capability database 140, which could havedifferent accuracies for the various ways that a wireless device 120could gather the information. Any uncertainty that the wireless device120 could have in knowing its location could also be reflected in theaccuracy weighting for the base station database 144.

Various types of location beacons could be used by the wireless device120 to aid in the location determination. This embodiment uses asatellite location beacon 152, but pseudolites and terrestrial beaconsystems such as LORAN could also be used. The more location references,generally, the better the location of the wireless device 120 can bedetermined.

This embodiment shows the almanac processor 122 separate from thecooperative base stations 112, but each cooperative base station 112 ora class of cooperative base stations 112 could have an almanac processor112 and/or databases 140,144 in other embodiments. Some embodimentscould integrate the almanac processor 122 into the wireless device 120.The base station and/or device capability databases 144,140 could alsobe in the wireless device 120 and updated periodically.

Referring next to FIG. 1B, another embodiment of the locationdetermination system 100-2 is shown. In some embodiments, the basestation database 144 is centrally located, but the base station database144 is distributed regionally or in portions relevant to eachcooperative base station 112 or a class of cooperative base stations 112as a local almanac 158 in the present embodiment. For example, a firstbase station 112-1, may store a portion of the base station database 114for its footprint and all adjacent base station footprints in a firstlocal almanac 158-1. As another example, the first local almanac 158-1may contain the base station database for all or select set of CDMA basestations. In yet another example, the first almanac 158-1 may not begeographically organized but contain the base stations which are part ofa particular service provider network. As the centrally-located basestation database 144 is updated, those changes are propagated to thevarious local almanacs 158 that might use the new information.

This embodiment does not use a satellite location beacon 152 or othertype of location beacon, but has one or more communication satellitesbase stations 154 for use in voice and/or data communication. Thisembodiment of the communication satellite base station 154 could, butdoes not, have a local almanac 158 and/or databases 140,144. Thecommunication satellite base station 154 relies upon the almanacprocessor 122 to produce tailored almanacs. A satellite ground station160 communicates with the almanac processor 122 by way of the WAN 110.

Referring next to FIG. 1C, yet another embodiment of the locationdetermination system 100-3 is shown. In this embodiment, a cooperativebase station 112 is coupled to a local area network (LAN) that iscoupled to an almanac processor 122 and device capability and basestation databases 140,144. The information in the device capability andbase station databases 140,144 could be periodically updated orreconciled with remote master versions of these databases using a WAN orthe like. The satellite base station 154 in this embodiment alsoincludes an almanac processor 122 and device capability and base stationdatabases 140,144, even though that level of detail is not shown in thefigure.

With reference to FIGS. 2A and 2B, diagrams of embodiments of asingle-cell location system 200 are shown. A cooperative base station112 has a cell footprint 204 in which it can communicate with thewireless device 120. FIG. 2A shows the uncooperative wireless basestation 124 within that cell footprint 204.

On occasion, the wireless device 120 is barely within the cell footprint204 to communicate with the cooperative base station 112, but has theability to communicate with uncooperative base stations 124 outside thiscell footprint as shown in FIG. 2B. A cell buffer zone 208 would includeuncooperative base stations 124 outside the range of the cooperativebase station 112, but possibly within range of a wireless device 120within range of the cooperative base station 112. An uncooperative basestation footprint 212 is shown for a base station 124 outside the cellfootprint, but within communication range of the wireless device 120.Including this base station 124 in the cell buffer zone 208 accommodatesthis scenario.

In this embodiment, the wireless device 120 is in communication range ofa single cooperative base station 112. In the cell footprint 204 of thecooperative base station 112, there are eleven uncooperative basestations 124. The cell buffer zone 208 has two more uncooperative basestations 124. When the almanac processor 122 receives a request for atailored almanac, information for the thirteen possible uncooperativebase stations are included.

In one embodiment, the cooperative base station 112 may determine arange to the wireless device 120 and the almanac processor 122 couldcull the list of thirteen to those that might fall within an annularring around the cooperative base station 112. The ring would be as thickas the range of the wireless device 120 when talking to the variousuncooperative base stations 124 in a particular mode plus some errorfactor from determining the range to the cooperative base station 112.For example, the wireless device 120 may have a range from thecooperative base station 112 of fifty measurement units with an errorfactor of ten percent. In one communication mode, the range from thewireless device 120 is fifteen units. In this example, the annular ringwould begin at a radius of thirty and extend to seventy measurementunits. Any base station 112,124 understanding that communication modeand within that annular footprint would be included in the tailoredalmanac. Of course, if the annular ring extended beyond the cell bufferzone 208 the radius of the ring would be curtailed appropriately.

As the wireless device 120 may have different modes of communication tothe various types of base stations, the thickness could be different foreach type of base station communication mode. Further, the wirelessdevice 120 may receive almanac information on other cooperative basestations 112 that the wireless device 120 was unaware of.

In another embodiment, the almanac processor 122 might cull the numberof base stations 112,124 included in the tailored almanac. In somecases, the density of base stations 112,124 is so great that includingadditional base stations 112,124 that are in close proximity would be oflittle aid in resolving the location of the wireless device 120.

In some embodiments, the almanac processor 122 might exclude basestations 112,124 that don't have any way to uniquely identify them. Forexample, if two base stations had the same station identifier and didnot provide any other codes to uniquely identify them, they both couldbe excluded from the tailored almanac. Often times, other identifiers inthe communication protocol can be combined with identifiers to create aunique identifier that distinguishes the base stations 112,124. In somecases, two or more base stations 112,124 that cannot be uniquelyidentified are so geographically separate that a unique identifier canbe formulated by knowing the geographic location of interest such thatthey could still be used. Only one would be included in any tailoredalmanac.

Referring next to FIGS. 3A and 3B, diagrams of embodiments of a cellsector location system 300 are shown. This embodiment has six cellsectors 304 for a cooperative base station 112, but other embodimentscould have any number of cell sectors. The wireless devices 120 in thecell footprint 204 are divided among the cell sectors 304 such that thebase station 112 knows which cell sector(s) 304 communicates with aparticular wireless device 120. The cell sector(s) that might have thewireless device 120 are forwarded to the almanac processor 122. Any basestations 112,124 within the cell sector(s) 304 are forwarded to thecooperative base station 112 for relay to the wireless device 120.

In the embodiment of FIG. 3A, a single cell sector 304 can communicatewith the wireless device 120. The almanac processor 122 would includethose base stations 112, 124 in that sector 304 along with those in asector buffer zone 308. The embodiment of FIG. 3B shows the wirelessdevice 120 close to the edge between two cell sectors 304 such that bothcan receive communication. The almanac processor 122 could provide thebase stations 112,124 in those two cell sectors 304 and a sector(s)buffer zone 308 around them to any wireless device 120 within or nearbythat area.

With reference to FIG. 4, a diagram of an embodiment of an overlappingcell location system 400 is shown. In this embodiment, two cooperativebase stations 112 can communicate with the wireless device 120 such thatthe overlap in the cell footprints 204 is presumed to be the location ofthe wireless device 120. The almanac processor 122 would query thedevice capability and base station databases 140,144 to determine how totailor an almanac for this overlapping region 404. A portion of the cellbuffer zone 208 that overlaps the cell buffer zone 208 of the other cellfootprint 204 and cell buffer zone 208 (and vice-versa) would also beanalyzed for base stations 112,124 to include in any tailored almanac.

Referring next to FIG. 5, a diagram of an embodiment of a trilaterationcell system 500 is shown. In this embodiment, the wireless device 120can communicate with three or more cooperative base stations112-1,112-2,112-3 that are geographically separate. A general locationof the wireless device 120 is determined by analyzing ranginginformation gathered by or from a number of cooperative base stations112. Time of arrival (TOA) readings from one cooperative base station112 reduces the general location to a ring around that base station 112.Two cooperative base stations 112 generating time difference of arrival(TDOA) ranging readings reduce the location to a hyperbole. Three ormore can resolve the general location even further. In this embodiment,time of arrival and/or time difference of arrival measurements are usedin the trilateration process.

However small the area becomes, a buffer around that area is determinedto compensate for the error in the determination and address the rangeof the wireless device 120 to base stations 112,124. The almanacprocessor 122 gathers information for the base stations 112,124 likelyto be in communication range for each communication mode supported bythe wireless device 120.

With reference to FIG. 6, a diagram of an embodiment of a hybridtrilateration system 600 is shown. This embodiment shows trilaterationwith different types of communication modes. The wireless device 120receives ranging information from a satellite location beacon 152 andcommunicates with two cooperative base stations 112-1,112-2. Between thethree 152,112-1,112-2, the general location can be trilaterated andforwarded to one of the cooperative base stations 112 in exchange for atailored almanac.

Referring next to FIG. 7, a diagram of an embodiment of an angularranging system 700 is shown. The cooperative base stations 112 in thisembodiment can estimate the angle of arrival (AoA) and distance to thewireless device. This ability allows determining a general location witha single cooperative base station 112. Where the cooperative basestation 112 can only determine AoA and not range, two cooperative basestations 112-1,112-2 can determine a general location.

The above embodiments do not rely upon uncooperative base stations 124to find an initial location estimate, but request a tailored almanacfrom cooperative base stations 112 for refined location estimations.Some embodiments could report the base stations 112,124 and locationbeacons seen and any ranging estimates to those as part of a locationrequest. The almanac processor 112 could take this information anddetermine a location using the device capability, mode of operation andbase station databases 140,144. In this embodiment, the initialgathering of location information is done without the benefit of atailored almanac. Where the almanac processor 122 determines a moreaccurate location is required, a tailored almanac could be produced thatindicates additional base stations 112,124 that are likely within rangeof the wireless device 120.

With reference to FIG. 8, a flow diagram of an embodiment of a processfor locating a position of a wireless device 120 that has nativelocation functions 800 is shown. The wireless device 120 couldtrilaterate to cooperative base stations 112 or satellite or groundlocation beacons to determine a general location in step 804. In step808, the wireless device 120 reports the location estimate and requestsa tailored almanac. Some wireless devices may store a base almanac ofbase stations 112,124 that is updated as new tailored almanacs arereceived.

In this embodiment, the location estimate could be further refinedoutside the wireless device in step 812. For example, the cooperativebase station 112 may have some location information from time of arrivalor time difference of arrival. The general location is forwarded to thealmanac processor 112. In step 816, the almanac processor 112 tailors analmanac by finding all base stations 112,124 that might be close enoughto use in determining a location of the wireless device 120. This takesinto account all the modes of communication of the wireless device 120that are compatible with the various base stations 112,124, the likelyrange in those modes, and the likely location of the wireless device120. That tailored almanac is sent over the WAN 110 to the cooperativebase station 112 and relayed to the wireless device in step 820.

In step 824, further location information is gathered by the wirelessdevice 120. This location information uses the tailored almanac andcould involve uncooperative base stations 124 as well as cooperativebase stations 112. In this embodiment, the wireless device 120 analyzesthe location information to refine the location estimate in step 828.The location estimate is reported to an cooperative base station in step832. During the process of determining a location, the wireless device120 may have location information for the base stations 112,124 in thetailored almanac or those not in the almanac yet. In step 836, thislocation information together with the almanac-related information suchas the identifications of the observed base stations is reported to ancooperative base station 112 and forwarded to the almanac processor 122for updating the base station database 144.

Referring next to FIG. 9, a flow diagram of another embodiment of aprocess 900 for locating a position of a wireless device 120 that haslimited location functions is shown. Some wireless devices have limitedability to independently determine their location. This embodimentrelies on other parts of the location determination system 100 toanalyze location information. In step 908, the wireless device 120requests a tailored almanac. The location is estimated by the variouscooperative base stations 112 in step 912.

That location estimate is passed to the almanac processor 122 fortailoring of almanac information in step 816. In step 820, the tailoredalmanac is sent to the wireless device 120. Step 824 gathers furtherlocation information using the tailored almanac to find uncooperativebase stations 124. In step 916, the gathered location information isforwarded to the cooperative base station 112. Step 928 refines thelocation estimate using the location information. The refinement may beperformed in the cooperative base station 112, the almanac processor 122or any other location in communication with the cooperative base station112. Any additional information gathered by the wireless device 120 isforwarded to the almanac processor 122 to refine the base stationdatabase 144.

With reference to FIG. 10, a diagram of an embodiment of system 1000that gathers location information from uncooperative base stations 124is shown. Once the tailored almanac is received by the wireless device120, it attempts to locate those base stations listed in the almanac.Shown in the embodiment of FIG. 10 is a dual-mode wireless device 120that supports two communication modes. One communication mode has afirst footprint 1012-1 and the second has a larger footprint 1012-2. Thetailored almanac would have all base stations 112,124 in the firstfootprint 1012-1 that use the first communication mode and all basestations 112,124 in the second footprint 1012-2 that use the secondcommunication mode.

In some embodiments, the almanac processor could perform a motionestimation for the wireless device 120 such that footprints 1012 areadjusted for the likely position of the wireless device 120 when thetailored almanac would be used. Other embodiments, could just expand thefootprint according the likely speed or maximum speed of the wirelessdevice 120 should it travel in any direction. In yet other embodiments,a history of handoffs between various base stations can be used totailor the almanac information.

Referring next to FIG. 11, a flow diagram of an embodiment of a process1100 for gathering location information from base stations 112,124 isshown. The process 1100 begins in step 1104 where the wireless device120 checks for base stations 112,124 in the tailored almanac. This couldbe done by randomly choosing base stations in the almanac 112,124. Insome embodiments, the base stations 112,124 could be pre-randomized sothat the wireless device 120 could take them in order.

In another embodiment, the almanac processor 122 could choose anotherscheme for organizing the base stations 112,124 to quickly find one. Forexample, they may be organized by communication mode and footprint 1012size. The footprint of the almanac is more quickly covered by usingcommunication modes with larger range.

Once one base station 112,124 in the almanac is found in step 1108, itmay be possible to exclude some of the base stations 112,124 in thealmanac. After running through the various base stations 112,124 to findthose in range of the wireless device 120, the distance to each isestimated in step 1112.

Uncooperative base stations 124 still give some information even thoughdata communication is not possible. They will identify themselves, whichindicates the wireless device 120 is close enough to communicate. Someuncooperative base stations 124 will indicate signal strength of areceived signal. Other uncooperative base stations 124 will acknowledgea message and that propagation time can be correlated to a distancetraveled. The signal strength of a signal from the uncooperative basestation 124 can intimate distance when the initial or expected signalstrength can be determined.

In some embodiments, the wireless device 120 gathers information on basestations 112,124 not included in the almanac in step 1116. Often thebase stations 112,124 self identify themselves. If resources areavailable, in step 1120 ranging may be performed to the unlisted basestations 112,124 for later report-back to the almanac processor. Inother embodiments, the footprint of the base station or the overlaps ofmore than one footprint can be analyzed to determine the generallocation of the wireless device 120.

With reference to FIG. 12, a diagram of another embodiment of system1200 that gathers location information from uncooperative base stations124 is shown. The depicted uncooperative base stations 124 are thoseidentified in a tailored almanac as likely to be in communication range.In this embodiment, three uncooperative base stations 124-1,124-4,124-5operate in a first communication mode with first communicationfootprints 1212-1, 1212-4,1212-5; two uncooperative base stations124-2,124-6 operate in a second communication mode with secondcommunication footprints 1212-2,1212-6; and one uncooperative basestation 124-3 operates in a third communication mode with a thirdcommunication footprint 1212-3. The current position of the wirelessdevice 120 only allows communication with three uncooperative basestations 124-2,124-3,124-4. Even without ranging measurements, this cannarrow down the location of the wireless device 120, but with rangingmeasurements, a very precise location can be determined.

The above description of the disclosed embodiments is provided to enableany person skilled in the art to make or use the disclosure. Variousmodifications to these embodiments will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other embodiments without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe embodiments shown herein but is to be accorded the widest scopeconsistent with the principles and novel features disclosed herein.

What is claimed is:
 1. A method at a location server for assisting inlocating a position of a mobile wireless device, the method comprising:obtaining, at the location server from the mobile device, locationinformation of an approximate location of the mobile wireless device;generating, at the location server, an almanac of terrestrial basestations, including terrestrial base station identifiers and associatedterrestrial base station locations, based at least in part on proximityof the terrestrial base station locations to the approximate location ofthe mobile wireless device, the almanac of terrestrial base stationscomprising at least one cooperative terrestrial base station that cancommunicate with the mobile wireless device in at least one mode and atleast one uncooperative WiFi terrestrial base station capable ofbi-directional wireless communications and configured to prevent dataand voice wireless communications with the mobile wireless device, theat least one uncooperative WiFi terrestrial base station beingconfigured to respond to the mobile device with signal information todetermine a distance between the at least one uncooperative WiFiterrestrial base station and the mobile wireless device; and providingthe almanac of terrestrial base stations from the location server to themobile wireless device.
 2. The method of claim 1, wherein the locationinformation comprises: coordinates of the approximate location of themobile wireless device; identities of base stations seen by the mobilewireless device; or a combination thereof.
 3. The method of claim 1,wherein the almanac of terrestrial base stations includes one or moregroups of base stations based on the approximate location for the mobilewireless device.
 4. The method of claim 1, further comprising:receiving, at the location server from the mobile wireless device, newlocation information for the mobile wireless device comprising locationsof the mobile wireless device and corresponding terrestrial base stationidentifiers of terrestrial base stations visible at the locations of themobile wireless device.
 5. The method of claim 4, wherein the almanac ofterrestrial base stations is provided from the location server to themobile wireless device via a cooperative wide-area-network base stationof the at least one cooperative terrestrial base station, and the newlocation information is received from the mobile wireless device via acooperative WiFi terrestrial base station.
 6. The method of claim 4,wherein at least one of the corresponding terrestrial base stationidentifiers corresponds to an uncooperative terrestrial base station notin the almanac of terrestrial base stations, the method furthercomprising updating the almanac of terrestrial base stations at thelocation server with the at least one of the corresponding terrestrialbase station identifiers.
 7. The method of claim 1, wherein obtainingthe location information comprises receiving, at the location serverfrom the mobile wireless device: coordinates of the approximate locationof the mobile wireless device; identities of, and range estimates to,base stations seen by the mobile wireless device; or a combinationthereof.
 8. The method of claim 1, wherein the almanac of terrestrialbase stations includes at least one wide-area-network base station, atleast one wireless-local-area-network base station, and at least oneBluetooth® base station.
 9. A system, in a location server, forassisting in locating a position of a mobile wireless device, the systemcomprising: means for obtaining, from the mobile device, locationinformation of an approximate location of the mobile wireless device;means for generating an almanac of terrestrial base stations, includingterrestrial base station identifiers and associated terrestrial basestation locations, based at least in part on proximity of theterrestrial base station locations to the approximate location of themobile wireless device, the almanac of terrestrial base stationscomprising at least one cooperative terrestrial base station that cancommunicate with the mobile wireless device in at least one mode and atleast one uncooperative WiFi terrestrial base station capable ofbi-directional wireless communications and configured to prevent dataand voice wireless communications with the mobile wireless device, theat least one uncooperative WiFi terrestrial base station beingconfigured to respond to the mobile device with signal information todetermine a distance between the at least one uncooperative WiFiterrestrial base station and the mobile wireless device; and means forproviding the almanac of terrestrial base stations from the locationserver to the mobile wireless device.
 10. The system of claim 9, whereinthe location information comprises: coordinates of the approximatelocation of the mobile wireless device; identities of base stations seenby the mobile wireless device; or a combination thereof.
 11. The systemof claim 9, wherein the almanac of terrestrial base stations includesone or more groups of base stations based on the approximate locationfor the mobile wireless device.
 12. The system of claim 9, furthercomprising: means for receiving, from the mobile wireless device,location information for the mobile wireless device comprising locationsof the mobile wireless device and corresponding terrestrial base stationidentifiers of terrestrial base stations visible at the locations of themobile wireless device.
 13. The system of claim 12, wherein at least oneof the corresponding terrestrial base station identifiers corresponds toan uncooperative terrestrial base station not in the almanac ofterrestrial base stations, the system further comprising means forupdating the almanac of terrestrial base stations with the at least oneof the corresponding terrestrial base station identifiers.
 14. Acomputer system, in a location server, the computer system comprising: anetwork interface; and a processor configured to: obtain, from a mobiledevice, location information of an approximate location of the mobilewireless device; generate an almanac of terrestrial base stations,including terrestrial base station identifiers and associatedterrestrial base station locations, based at least in part on proximityof the terrestrial base station locations to the approximate location ofthe mobile wireless device, the almanac of terrestrial base stationscomprising at least one cooperative terrestrial base station that cancommunicate with the mobile wireless device in at least one mode and atleast one uncooperative WiFi terrestrial base station capable ofbi-directional wireless communications and configured to prevent dataand voice wireless communications with the mobile wireless device, theat least one uncooperative WiFi terrestrial base station beingconfigured to respond to the mobile device with signal information todetermine a distance between the at least one uncooperative WiFiterrestrial base station and the mobile wireless device; and provide thealmanac of terrestrial base stations from the location server to themobile wireless device.
 15. The computer system of claim 14, wherein thelocation information comprises: coordinates of the approximate locationof the mobile wireless device; identities of base stations seen by themobile wireless device; or a combination thereof.
 16. The computersystem of claim 15, wherein the location information comprisesidentities of base stations seen by the mobile wireless device, andwherein the processor is configured to determine the approximatelocation of the mobile wireless device based, at least in part, on theidentities of base stations seen by the mobile wireless device.
 17. Thecomputer system of claim 14, wherein the almanac of terrestrial basestations includes one or more groups of base stations based on theapproximate location for the mobile wireless device.
 18. The computersystem of claim 14, wherein the processor is further configured to:receive, from the mobile wireless device, location information for themobile wireless device comprising locations of the mobile wirelessdevice and corresponding terrestrial base station identifiers ofterrestrial base stations visible at the locations of the mobilewireless device.
 19. The computer system of claim 18, wherein at leastone of the corresponding terrestrial base station identifierscorresponds to an uncooperative terrestrial base station not in thealmanac of terrestrial base stations, the processor being furtherconfigured to update the almanac of terrestrial base stations with theat least one of the corresponding terrestrial base station identifiers.20. A tangible, non-transitory computer-readable medium, having storedthereon computer-readable instructions for instructing a location serverto assist in locating a position of a mobile wireless device, thecomputer-readable instructions comprising instructions configured tocause a computer to: obtain, from the mobile device, locationinformation of an approximate location of the mobile wireless device;generate an almanac of terrestrial base stations, including terrestrialbase station identifiers and associated terrestrial base stationlocations, based at least in part on proximity of the terrestrial basestation locations to the approximate location of the mobile wirelessdevice, the almanac of terrestrial base stations comprising at least onecooperative terrestrial base station that can communicate with themobile wireless device in at least one mode and at least oneuncooperative WiFi terrestrial base station capable of bi-directionalwireless communications and configured to prevent data and voicewireless communications with the mobile wireless device, the at leastone uncooperative WiFi terrestrial base station being configured torespond to the mobile device with signal information to determine adistance between the at least one uncooperative WiFi terrestrial basestation and the mobile wireless device; and provide the almanac ofterrestrial base stations from the location server to the mobilewireless device.
 21. The computer-readable medium of claim 20, whereinthe location information comprises: coordinates of the approximatelocation of the mobile wireless device; identities of base stations seenby the mobile wireless device; or a combination thereof.
 22. Thecomputer-readable medium of claim 20, wherein the almanac of terrestrialbase stations includes one or more groups of base stations based on theapproximate location for the mobile wireless device.
 23. Thecomputer-readable medium of claim 20, further comprising instructionsconfigured to cause the computer to: receive, from the mobile wirelessdevice, location information for the mobile wireless device comprisinglocations of the mobile wireless device and corresponding terrestrialbase station identifiers of terrestrial base stations visible at thelocations of the mobile wireless device.
 24. The computer-readablemedium of claim 23, wherein at least one of the correspondingterrestrial base station identifiers corresponds to an uncooperativeterrestrial base station not in the almanac of terrestrial basestations, the computer-readable medium further comprising instructionsconfigured to cause the computer to update the almanac of terrestrialbase stations with the at least one of the corresponding terrestrialbase station identifiers.